Moments
Moment of a force about a point defined as force × perpendicular distance from the point to the line of action of the force; torque.
Couple of a pair of equal and opposite forces defined as force × perpendicular distance between the lines of action of the forces.
The principle of moments and its applications in simple balanced situations.
Centre of mass; calculations of the position of the centre of mass of a regular lamina are not expected.

Refraction at a plane surface
Refractive index of a substance s,
Candidates are not expected to recall methods for determining refractive indices.
Law of refraction for a boundary between two different substances of refractive indices and in the form

Total internal reflection including calculations of the critical angle at a boundary between a substance of refractive index and a substance of lesser refractive index or air;
Simple treatment of fibre optics including function of the cladding with lower refractive index around central core limited to step index only; application to communications.

DiffractionAppearance of the diffraction pattern from a single slit.
The plane transmission diffraction grating at normal incidence; optical details of the spectrometer will not be required.
Derivation of , where n is the order number.
Applications; e.g. to spectral analysis of light from stars.